What does this strategy say about the Lib Dems today? Is it part of a wider coalition talks with the Tories or simply a survival strategy?

Whatever the motive, I think it's a strategy the Lib Dems may come to regret. (And I don't say this in some kind of macho, fighting-talk way - "You will regret that!")

There's no doubting that the popularity and electoral fortunes of the Labour party look pretty poor right now. But from the recent popularity tests - the local elections, the London elections and the byelections - there's little evidence that the Lib Dems are benefiting from Labour's poor performance.

In fact there are examples of the opposite: in my own area we won a local election seat (convincingly) which last year we lost to the Lib Dems. In the recent byelections the Lib Dems, by their own standards and compared to byelections in recent years, did pretty poorly.

So perhaps the Lib Dems' calculation is based on their own polling, which shows that their most likely source of votes at the next election is from people who are fed up with the government but unconvinced by the Tories and that the majority of these people live in Labour/Lib Dem seats and not Tory/Lib Dem seats.

The last general election undoubtedly marked a high watermark for the third party: they were on the side of the public majority over Iraq, the government was unpopular, yet the Tories were still seen as "nasty".

Consequently they made gains from both parties - some, including my own prospective seat, Manchester Withington, a surprise even to themselves.

The Lib Dem response to this is to narrow their own appeal, withdrawing from one of their political flanks, not broadening it.

It's their broad (ie all things to all people) base which has often been the key to their electoral success. The Lib Dems are seen as unthreatening, as a risk-free vote, a vote of little consequence. That's how many I speak to talk about their choice. They want to send a message but they don't want a Tory government.

Giving the Tories a free ride and focusing all their fire on Labour in an attempt to unseat the government blows a hole in this unthreatening, touchy-feely appearance.